1. Field of the Invention
This invention relates to a driving method for an image display apparatus.
2. Description of the Related Art
In recent years, an image display apparatus such as, for example, a color liquid crystal display apparatus has a problem in increase of the power consumption involved in enhancement of performances. Particularly as enhancement in definition, increase of the color reproduction range and increase in luminance advance, for example, in a color liquid crystal display apparatus, the power consumption of a backlight increases. Attention is paid to an apparatus which solves the problem just described. The apparatus has a four-subpixel configuration which includes, in addition to three subpixels including a red displaying subpixel for displaying red, a green displaying subpixel for displaying green and a blue displaying subpixel for displaying blue, for example, a white displaying subpixel for displaying white. The white displaying subpixel enhances the brightness. Since the four-subpixel configuration can achieve a high luminance with power consumption similar to that of display apparatus in related arts, if the luminance may be equal to that of display apparatus in related arts, then it is possible to decrease the power consumption of the backlight and improvement of the display quality can be anticipated.
For example, a color image display apparatus disclosed in Japanese Patent No. 3167026 (hereinafter referred to as Patent Document 1) includes:
means for producing three different color signals from an input signal using an additive primary color process; and
means for adding the color signals of the three hues at equal ratios to produce an auxiliary signal and supplying totaling four display signals including the auxiliary signal and three different color signals obtained by subtracting the auxiliary signal from the signals of the three hues to a display unit.
It is to be noted that a red displaying subpixel, a green displaying subpixel and a blue displaying subpixel are driven by the three different color signals while a white displaying subpixel is driven by the auxiliary signal.
Meanwhile, Japanese Patent No. 3805150 (hereinafter referred to as Patent Document 2) discloses a liquid crystal display apparatus which includes a liquid crystal panel wherein a red outputting subpixel, a green outputting subpixel, a blue outputting subpixel and a luminance subpixel form on main pixel unit so that color display can be carried out, including:
calculation means for calculating, using digital values Ri, Gi and Bi of a red inputting subpixel, a green inputting subpixel and a blue inputting subpixel obtained from an input image signal, a digital value W for driving the luminance subpixel and digital values Ro, Go and Bo for driving the red inputting subpixel, green inputting subpixel and blue inputting subpixel;
the calculation means calculating such values of the digital values Ro, Go and Bo as well as W which satisfy a relationship ofRi:Gi:Bi=(Ro+W):(Go+W):(Bo+W)and with which enhancement of the luminance from that of the configuration which includes only the red inputting subpixel, green inputting subpixel and blue inputting subpixel is achieved by the addition of the luminance subpixel.
Further, PCT/KR 2004/000659 (hereinafter referred to as Patent Document 3) discloses a liquid crystal display apparatus which includes first pixels each configured from a red displaying subpixel, a green displaying subpixel and a blue displaying subpixel and second pixels each configured from a red displaying subpixel, a green displaying subpixel and a white displaying subpixel and wherein the first and second pixels are arrayed alternately in a first direction and the first and second pixels are arrayed alternately also in a second direction. The Patent Document 3 further discloses a liquid crystal display apparatus wherein the first and second pixels are arrayed alternatively in the first direction while, in the second direction, the first pixels are arrayed adjacent each other and besides the second pixels are arrayed adjacent each other.